diff --git a/common/src/main/resources/modernfix.accesswidener b/common/src/main/resources/modernfix.accesswidener
index 73cc7586..4dd4468c 100644
--- a/common/src/main/resources/modernfix.accesswidener
+++ b/common/src/main/resources/modernfix.accesswidener
@@ -38,3 +38,4 @@ accessible class net/minecraft/server/level/ChunkMap$DistanceManager
 accessible class net/minecraft/world/level/chunk/PalettedContainer$Data
 accessible field net/minecraft/server/MinecraftServer resources Lnet/minecraft/server/MinecraftServer$ReloadableResources;
 accessible class net/minecraft/server/MinecraftServer$ReloadableResources
+accessible method net/minecraft/client/gui/screens/Screen addRenderableWidget (Lnet/minecraft/client/gui/components/events/GuiEventListener;)Lnet/minecraft/client/gui/components/events/GuiEventListener;
\ No newline at end of file
diff --git a/forge/src/main/java/org/embeddedt/modernfix/forge/datagen/RuntimeDatagen.java b/forge/src/main/java/org/embeddedt/modernfix/forge/datagen/RuntimeDatagen.java
new file mode 100644
index 00000000..d2e32a28
--- /dev/null
+++ b/forge/src/main/java/org/embeddedt/modernfix/forge/datagen/RuntimeDatagen.java
@@ -0,0 +1,80 @@
+package org.embeddedt.modernfix.forge.datagen;
+
+import net.minecraft.client.Minecraft;
+import net.minecraft.client.gui.components.Button;
+import net.minecraft.client.gui.screens.TitleScreen;
+import net.minecraft.network.chat.TextComponent;
+import net.minecraft.server.packs.PackResources;
+import net.minecraft.server.packs.PackType;
+import net.minecraft.server.packs.resources.MultiPackResourceManager;
+import net.minecraftforge.api.distmarker.Dist;
+import net.minecraftforge.client.event.ScreenEvent;
+import net.minecraftforge.common.data.ExistingFileHelper;
+import net.minecraftforge.data.loading.DatagenModLoader;
+import net.minecraftforge.eventbus.api.SubscribeEvent;
+import net.minecraftforge.fml.ModLoader;
+import net.minecraftforge.fml.common.Mod;
+import net.minecraftforge.fml.util.ObfuscationReflectionHelper;
+import net.minecraftforge.forge.event.lifecycle.GatherDataEvent;
+import org.embeddedt.modernfix.ModernFix;
+
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.*;
+import java.util.stream.Collectors;
+
+@Mod.EventBusSubscriber(value = Dist.CLIENT)
+public class RuntimeDatagen {
+    private static final String RESOURCES_OUT_DIR = getPropertyOrBlank("modernfix.datagen.output");
+    private static final String RESOURCES_IN_DIR = getPropertyOrBlank("modernfix.datagen.existing");
+    private static final String MODS_LIST = getPropertyOrBlank("modernfix.datagen.mods");
+    private static final String EXISTING_MODS_LIST = getPropertyOrBlank("modernfix.datagen.existing_mods");
+    private static final boolean IS_FLAT = Boolean.getBoolean("modernfix.datagen.flat");
+
+    private static String getPropertyOrBlank(String name) {
+        String val = System.getProperty(name);
+        if(val == null || val.length() == 0)
+            return "";
+        else
+            return val;
+    }
+
+    public static boolean isDatagenAvailable() {
+        return RESOURCES_OUT_DIR.length() > 0;
+    }
+
+    public static void runRuntimeDatagen() {
+        ObfuscationReflectionHelper.setPrivateValue(DatagenModLoader.class, null, true, "runningDataGen");
+        Set<String> mods = new HashSet<>(Arrays.stream(MODS_LIST.split(",")).collect(Collectors.toSet()));
+        ModernFix.LOGGER.info("Beginning runtime datagen for " + mods.size() + " mods...");
+        Set<String> existingMods = new HashSet<>(Arrays.stream(EXISTING_MODS_LIST.split(",")).collect(Collectors.toSet()));
+        Set<Path> existingPacks = new HashSet<>(Arrays.stream(RESOURCES_IN_DIR.split(",")).map(Paths::get).collect(Collectors.toSet()));
+        Path path = Paths.get(RESOURCES_OUT_DIR);
+        GatherDataEvent.DataGeneratorConfig dataGeneratorConfig = new GatherDataEvent.DataGeneratorConfig(mods, path, Collections.emptyList(),
+                true, true, true, true, true, mods.isEmpty() || IS_FLAT);
+        if (!mods.contains("forge")) {
+            //If we aren't generating data for forge, automatically add forge as an existing so mods can access forge's data
+            existingMods.add("forge");
+        }
+        ExistingFileHelper existingFileHelper = new ExistingFileHelper(existingPacks, existingMods, true, null, null);
+        /* Inject the client pack resources from us */
+        MultiPackResourceManager manager = ObfuscationReflectionHelper.getPrivateValue(ExistingFileHelper.class, existingFileHelper, "clientResources");
+        List<PackResources> oldPacks = new ArrayList<>(manager.listPacks().collect(Collectors.toList()));
+        oldPacks.add(Minecraft.getInstance().getClientPackSource().getVanillaPack());
+        ObfuscationReflectionHelper.setPrivateValue(ExistingFileHelper.class, existingFileHelper, new MultiPackResourceManager(PackType.CLIENT_RESOURCES, oldPacks), "clientResources");
+        ModLoader.get().runEventGenerator(mc->new GatherDataEvent(mc, dataGeneratorConfig.makeGenerator(p->dataGeneratorConfig.isFlat() ? p : p.resolve(mc.getModId()), dataGeneratorConfig.getMods().contains(mc.getModId())), dataGeneratorConfig, existingFileHelper));
+        dataGeneratorConfig.runAll();
+        ObfuscationReflectionHelper.setPrivateValue(DatagenModLoader.class, null, false, "runningDataGen");
+        ModernFix.LOGGER.info("Finished runtime datagen.");
+    }
+
+    @SubscribeEvent
+    public static void onInitTitleScreen(ScreenEvent.InitScreenEvent.Post event) {
+        if(isDatagenAvailable() && event.getScreen() instanceof TitleScreen) {
+            TitleScreen screen = (TitleScreen)event.getScreen();
+            screen.addRenderableWidget(new Button(screen.width / 2 - 100 - 50, screen.height / 4 + 48, 50, 20, new TextComponent("DG"), (arg) -> {
+                runRuntimeDatagen();
+            }));
+        }
+    }
+}